Hmm, I thought the music was one of the weaker aspects of this trailer :/ a lot of it seemed to be just a continuous noise (this could just be the bad quality of the video itself), not really drawing me into what's happening or the themes at play.
The music in the RL trailer at hand was fairly neat, but I think the same sound and themes could have been captured with an original tune; in my mind, that's even cooler than using existing music, and not all that hard with the amount of talented musicians willing to write music for free or even for a small price. Also, a musician would probably be able to capture the game much better than a pre-written tune could, as they can alter every nuance of their songs to suit the game for which they are designed.
But this seems to be just a lazy, for-the-heck-of-it trailer, so who really cares? If it's a serious promotional trailer, than I'd definitely suggest some original tunes.